Cellular and fibrous materials coated with an adhesive which can be reactivated are used in a variety of applications. For example, automotive trim panels including headliners can be made by using an adhesive coated panel as a shell or substrate and laminating a decorative cover to the adhesive coated side of the panel. These adhesive coated panels can also be used in the manufacture of other automotive products such as floor pads, hood liners, trunk liners, seating and door panels.
Adhesives can be applied to cellular or fibrous material in many ways, including sprinkling dry adhesive powder, spraying and hot melt printing. It is important to control the amount of adhesive applied in order to avoid waste and disposal problems and also to avoid penetration of the adhesive into the cell and fiber structure of the material. Excess adhesive which finds its way into the cells and fibrous structure of the material often has an undesirable effect on the laminated composite and also increases quantity required and the cost of same.
The particle size of dry adhesive powder is usually small and when applied by sprinkling, much of the adhesive will drop into the cells or fibrous structure of the material rather than remain on the surface where it is needed to provide a second step quality lamination.
In conventional spray methods, multiple overlapping nozzles are used to provide continuous coverage. Overspray beyond the edges of the material is often considered necessary, also to insure continuous coverage. However, the use of overlapping nozzles and overspraying results in waste and disposal problems. Also, adhesive applied in liquid form penetrates into the cell and fiber structure of the material.
Methods of coating materials with adhesive are disclosed in U.S. Pat. No. 4,055,688 to Caratsch, U.S. Pat. No. 4,264,644 to Schaetti, U.S. Pat. No. 4,571,351 to Schaetti, U.S. Pat. No. 4,139,613 to Hefele and U.S. Pat. No. 4,815,660 to Boger. Caratsch (U.S. Pat. No. 4,055,688) in a first step elevates temperature of the adhesive "to its sinter temperature". The adhesive is then transferred onto the surface of a heated printing roll and as the flexible material passes between the printing roll and a contact pressure roll, the adhesive is then released onto the surface of the web material that is in contact with the printing roll.
The process disclosed in Schaetti (U.S. Pat. No. 4,264,644) uses an engraved roller to apply a specified pattern of synthetic powdered adhesive to a flexible textile material. Thermoplastic adhesive is dispensed from a supply container onto an engraved roller and the flexible textile is heated with radiant heat to a temperature sufficient to melt the adhesive and allow same to adhere to the textile and release from the water cooled printing roll.
The method disclosed by Schaettl (U.S. Pat. No. 4,571,351) for coating a flexible cloth with a synthetic powdery product dispenses powdered adhesive from a reservoir onto the surface of an engraved roller which has been preheated with non-contact radiant heaters. The cloth is brought around a second roller which applies pressure to the cloth and presses it into recesses in the engraved roller to pick up the softened adhesive.
The process disclosed in Hefele (U.S. Pat. No. 4,139,613) is for the application of thermoplastic powdered adhesive onto the outer surface of a flexible textile or foam. This process teaches a method of application of two layers of adhesive, superposed one on the other onto a flexible material. This process also uses an engraved roller or other method which provides a predetermined quantity of adhesive with a fixed pattern.
The method in Boger (U.S. Pat. No. 4,815,660) is for spraying hot melt adhesive using at least two spray guns. The spray from the nozzles of these spray guns would have to overlap making it difficult to maintain uniformity of coverage.